Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Determinants

Question:

If A is an invertible matrix of order 3, then

Match List-I with List-II

List-I

List-II

(A) $|adj\,A|$

(I) $8|A|$

(B) $|A(adj\, A)|$

(II) $|A|^2$

(C) $|2A|$

(III) $\frac{1}{|A|}$

(D) $|A^{-1}|$

(IV) $|A|^3$

Choose the correct answer from the options given below:

Options:

(A)-(II), (B)-(IV), (C)-(I), (D)-(III)

(A)-(I), (B)-(II), (C)-(III), (D)-(IV)

(A)-(III), (B)-(IV), (C)-(I), (D)-(II)

(A)-(IV), (B)-(III), (C)-(II), (D)-(I)

Correct Answer:

(A)-(II), (B)-(IV), (C)-(I), (D)-(III)

Explanation:

The correct answer is Option (1) → (A)-(II), (B)-(IV), (C)-(I), (D)-(III)

List-I

List-II

(A) $|adj\,A|$

(II) $|A|^2$

(B) $|A(adj\, A)|$

(IV) $|A|^3$

(C) $|2A|$

(I) $8|A|$

(D) $|A^{-1}|$

(III) $\frac{1}{|A|}$

Given: $A$ is an invertible $3\times 3$ matrix.

(A) $|\text{adj }A|$

For $n\times n$: $|\text{adj }A| = |A|^{\,n-1}$. Here $n=3$, so $|\text{adj }A| = |A|^2$. Matches (II)

(B) $|A(\text{adj }A)|$

$A(\text{adj }A)=|A|I$, so determinant $=|A|^3$. Matches (IV)

(C) $|2A|$

$|kA|=k^n|A|$ with $n=3$, so $|2A|=2^3|A|=8|A|$. Matches (I)

(D) $|A^{-1}|$

$|A^{-1}|=\frac{1}{|A|}$. Matches (III)

The correct matching is: A–II, B–IV, C–I, D–III.